Can anyone tell me if soy lecithin will give tempered milk chocolate a more uniform appearance?

I am frustrated with what seems to be a "unmixed "appearance after removing milk chocolate from bar molds. I typically process the chocolate in a melanger for at least 3 days and add milk powder, sugar and cocoa butter about 24 hrs. into the 3 day cycle of grinding the nibs.  After the tempering process, I put it into poly molds. It has a nice snap but each bar seems to be different in that some are glossy and some are not. Some bars have dull spots and some have streaks. It doesn't appear to be a bloom problem but I am not sure. I recently ordered some soy lecithin to add to the mix in hopes that it might correct the problem but would like to hear from the experts here before doing so. Also, the lecithin is in liquid form and I'm not sure how much to add. Lastly, the temperature in the room where I'm doing all my work averages around 65 degrees F. and 41% humidity. Any comments are welcome.

Thanks